Description

Page : 0

Sondrestrom Lidar Operation Log

Operator(s) : Christian, Have, Pedersen, Christian, Have, Pedersen, Christian Have Pedersen
Purpose : Daq. on 532nm and Raman
Date(s) : 080320 - 080320
File(s) : L20080304_001 - L20080320_002
Comments : Before this experiment the primary and secondary mirrors have been adjusted.
Some adjustment was needed, so an improved signal in this experiment was
expected.
It turned out, that the low alt. return is still difficult to handle.
But the 532nm profile has been pushed up ~5km, which of course is a good sign.
Also, an ekstra mount has been fitted inside the telescope; this gives the frontend
tube a solid fixed position. This experiment did show a solid, consistent profile,
which verifies that the frontend is now fixed.
Flipped chopper in the Rayleigh path;This turned out to be surprisingly effectful
in terms of handling the low alt. return. Was able to almost eliminate low alt.
return using just the chopper delay (Which really is the point).
Logfile : l0803190.log

Setup:0

Page : 1
[Variables]
Rayleigh Power=
Chopper delay=

[0]
front end Iris=not_installed
Rayleigh System=On
Rayleigh Field stop=0.5mm
Rayleigh path attenuation=0dB
Dye System=On
Sodium Field stop=0.5mm
Etalon=Out
Daystar=Out
Polarizer=In
HalfWave Plates=Tracking
Rayleigh Filter=2:532(.5nm)
Rayleigh seeding=off

Logsheet:0

Page : 2

Sondrestrom Lidar Operation Log

Log Sheet 1 of 3
Operators : Christian Have Pedersen
Date(s) : 080320 - 080320
File(s) : L20080304_001 - L20080320_001

Files	Time [UT]	Comments	Cnt	S	Ope
L20080304_001	02:35:00	Start of experiment		0	cp
L20080320_000	04:50:34	Phew. Still having problems converging and strugling with		0	cp
		the low alt. peak.
L20080320_000	05:06:12	Since the last time; The primary and secondary mirrors		0	cp
		have been adjusted.
L20080320_001	05:38:43	The frontend has been properly fixed inside the telescope,		0	cp
		which shows in the consistent profile.
		It is still very hard to converge and adjust the iris, so that
		an acceptable profile is acquired.
		And the low alt. "Hump" is still a problem
L20080320_001	06:16:09	Hard to improve in terms of counts and low alt. return.		0	cp
		Now trying to find a profile without afterpulsing
L20080320_001	06:18:38	Still some AP (After Pulsing). Will now push up chopper a		0	cp
		a notch.
L20080320_001	06:20:40	This profile is a small progress from before adjusting the	265	0	cp
		1. and 2. mirrors.
		We are getting a little higher as well +5km
		Still difficult to adjust out the low alt. return.
		There are some minor details in the alignment of the
		RX path, but I do not think they will provide much improvement
L20080320_001	06:31:37	Now the HW plates will be flipping.	258	0	cp
L20080320_001	06:41:26	The counts differs between 250 and 70 on flipped records	250	0	cp
L20080320_001	06:42:29		72	0	cp
L20080320_001	06:43:49		265	0	cp

Logsheet:1

Page : 3

Sondrestrom Lidar Operation Log

Log Sheet 2 of 3
Operators : Christian Have Pedersen
Date(s) : 080320 - 080320
File(s) : L20080320_001 - L20080320_002

Files	Time [UT]	Comments	Cnt	S	Ope
L20080320_001	06:45:17	It really is a relief to see a reliable profile with a consistent		0	cp
		profile shape and solid counts.
L20080320_001	06:47:27	It should be possible to get a little better counts and maybe		0	cp
		a little higher, when fine tuning the RX alignment.
		But the source of the low alt. return is still not found.	254
L20080320_001	07:15:09		87	0	cp
L20080320_001	07:21:21		248	0	cp
L20080320_001	07:26:31		94	0	cp
L20080320_001	07:26:58	As the last thing tonight, the rayleigh chopper will be flipped		0	cp
		So that the focal point will be chopped from the other side.
		This means dismantling some of the Raman path, so the
		Raman daq. will be shut down now.
L20080320_001	07:29:48	Raman app. crashed. hmmm....	244	0	cp
L20080320_001	07:44:42	Thats an ugly profile. Of course the chopper delay is rubbish		0	cp
		now; Furthermore, there was not enough real estate to do
		this quick and good, so the chopper blade is not chopping
		through the focal point. But I think it is close enough to
		get a feeling of the difference. Ref: Chopper delay in original
		setup was 35. Will now find a proper delay.
L20080320_002	08:12:30	Stopping flipping.		0	cp
L20080320_002	08:15:31	Interesting. With the chopper flipped, handling the low alt.		0	cp
		return is easy, just raise the chopper heigth and it is gone.
L20080320_002	08:17:23	The profile does not look good now, will try and improve it		0	cp
		Bear in mind that the focal point is off by ~2mm.

Logsheet:2

Page : 4

Sondrestrom Lidar Operation Log

Log Sheet 3 of 3
Operators : Christian Have Pedersen
Date(s) : 080320 - 080320
File(s) : L20080320_002 - L20080320_002

Files	Time [UT]	Comments	S	Ope
L20080320_002	08:18:53	Also, the peak of the profile is sharpe, even though it is	0	cp
		not chopping through the focal point.
		I will try and raise the profile.
L20080320_002	08:26:28	Well the profile is crap. But it is really, really interesting	0	cp
		to see the effect on the low alt. return.
		Frontend iris and 2. iris are both wide open. The chopper
		takes care of the low alt. return.
		I really need to spend some time on repositioning the
		chopper, so that it is in the focal point of the relay.
		However, if this is going to be a solution, some rethinking of
		the RX layout needs to be done. The chopper blocks the
		RAMAN path as it is now.
L20080320_002	08:31:36	End of experiment	0	cp